Device with a screw plug and a range of devices

ABSTRACT

A device having at least one screw plug for screwing into a first tapped hole of a housing or housing part of the device, the at least one screw plug including a device for sealing, such as a sealing ring, for the connection to the housing in a manner forming a seal, e.g., against the escape of oil. Introduced into the screw plug is a second tapped hole by which a sensor is releasably connectable, e.g., is able to be screwed in. The screw plug includes an end stop for conducting acoustical waves and for the simultaneous mechanical limit for screwing in the screw plug.

FIELD OF THE INVENTION

[0001] The present invention relates to a device and a production seriesof devices.

BACKGROUND INFORMATION

[0002] Industrial gear units are generally conventional which includelubricant that must be poured in or removed and exchanged duringassembly and/or servicing. Therefore, many gear units have a tapped holein their housing which is closed by a screw plug. To save space, this isprovided with a hexagonal recess so that it does not protrude at all orprotrudes as little as possible from the housing.

[0003] German Published Patent Application No. 198 42 173 describes afastening element having a self-locating screw connection. A vibrationsensor is able to be mounted on the fastening element.

[0004] A disadvantage in that case is that it is not possible to screwin the vibration sensor, since the fastening element has a bore holestarting from the base (FIG. 1 of German Published Patent ApplicationNo. 198 42 173, reference numeral 32) for improving the elasticity ofthe fastening element (German Published Patent Application No. 198 42173, column 3, lines 41-45). The vibration sensor is thus pasted on orthe like. Therefore, the structure-borne noise to be detected must betransmitted through the screw thread and the core (German PublishedPatent Application No. 198 42 173, reference numeral 22) and theadhesive connection. Consequently, only a single essential path existsfor the sound, and it is not possible to achieve a good signal-to-noiseratio, since each junction, i.e., each connecting point, worsens thesignal-to-noise ratio. It is also disadvantageous that when screwing inthe fastening element, shavings develop which trigger oil contaminationand later, even destruction of a device. In addition, because of theconical design, the axial guidance during the screw-in operation ispoor. Therefore, the fastening element is at an unpredictable angle, andsignal-to-noise ratios of different quality come about for the sensorsignals depending on the angle. In the same manner, there is no definedstop face, and therefore also no defined pressure. As a result, thesealing function is also not defined, and the signal-to-noise ratiosfluctuate for the same reasons, as well. There is also no reusecapability, since each time the fastening element is loosened andscrewed in again, it sits ever more loosely in the base. Moreover, thereis even the danger that if the tightening torque is too great, theO-ring (German Published Patent Application No. 198 42 173, referencenumeral 4) will be destroyed, and therefore the sealing function can nolonger be reliably ensured. In addition, the surface of the base and ofthe hexagon head is not machined, and already for this reason, a sealingfunction cannot be ensured.

[0005] It is an aspect of the present invention to provide as compactand cost-effective a production series of gear units as possible, inwhich gear units having vibration sensors may be also included, andwhich may provide great flexibility for meeting customer wishes.

SUMMARY

[0006] In accordance with an example embodiment of the presentinvention, the foregoing aspect with respect to the device may beachieved according to the features described herein, and with respect tothe production series of devices, may be achieved according to thefeatures described herein.

[0007] Features of an example embodiment of the present invention withrespect to the device may include that the screw plug is connectable tothe housing in a manner forming a seal, e.g., against the escape of oil,and that a second tapped hole, by which a sensor is able to bereleasably connected, is introduced into the screw plug.

[0008] A compact and cost-effective production series of devices maytherefore be possible which also includes gear units without or withvibration sensors, and may which may offer great flexibility infulfilling customer wishes. If the customer only wants a device, forexample, a gear unit or a geared motor, without vibration sensor, thedevice may be delivered with a screw plug, which may be either designedconventionally or according to an example embodiment of the presentinvention. However, if the customer wants a device having vibrationsensors, the sensor is screwed into the screw plug. Thus, even sold anddelivered devices may be modified or retrofitted quickly and easily, ormay temporarily be equipped with the vibration sensors for analyses. Afurther aspect may be that no additional surface of the housing may needto be machined for mounting sensors. Therefore, machining processes maybe reduced.

[0009] Moreover, different kinds of sensors may be used as the sensor.However, an example embodiment of the present invention may provideadvantages in the case of vibration sensors, since they may be able tobe connected imperviously, with high contact pressure and as directly aspossible to the sound source. The use of tapped holes, e.g., may permitgood coupling from a standpoint of acoustical engineering. Since thetightening torque may be designed to be different for the first and thesecond tapped hole, use of a suitably high tightening torque may offer agreat degree of selectability for the coupling of the vibration sensorto the housing in terms of acoustical engineering. On the other hand,the sensor itself may be connectable with its stipulated tighteningtorque to the second tapped hole, and may thus not be destroyed orunacceptably stressed. Therefore, there may be great variance within theproduction series, accompanied by good coupling from the standpoint ofacoustical engineering as a shared feature.

[0010] In an example embodiment, in the screwed-in state, the screw plugprojects in such a manner from the housing with an external formprotruding such that it is releasable or connectable again with a toolthat is releasably connectable with form locking. The external form maybe an external hexagon. A greater tightening torque may be applied thanwith an internal hexagon. In addition, the sensor and the screw plug mayeach be connectable separately.

[0011] In an example embodiment, the second tapped hole is introducedwith sinking into the screw plug for the releasable connection to asensor that has an external thread corresponding to the second tappedhole and a cone section corresponding to the sinking. This may providethat a mechanically stable connection may be produced which is good fromthe standpoint of acoustical engineering, thus, with low damping. Thescrew plug may further be able to be made of metal, and thus a hightightening torque may be applied, which means the sound damping at thesecond tapped hole with sinking may be reduced. In spite of the factthat the screw plug is made of metal, the connection of the screw plugtoward the housing may be provided in an impervious manner using asealing ring. In an example embodiment, the sensor may be a vibrationsensor and/or a sensor for detecting acoustic vibrations at least in asubrange of the frequency range from 0 Hz to 10 MHz. Low frequencies maybe detectable, for example, using a so-called knock sensor. Mid and/orhigh frequencies may be detectable using a sensor for sound orstructure-borne noise, thus vibrations into the high ultrasonic range.

[0012] In an example embodiment, the screw plug may include an end stopfor conducting acoustical waves and at the same time for a mechanicallimit for the screw-in operation. With the aid of the end stop, asubstantial portion of the sound transmission may be able to be realizedin response to the application of a suitably high force. The end stop ispressed directly onto the sealing surface allocated to it and exhibitinga high surface quality. Thus, only low damping exists, even at mid orhigh frequencies. In addition, because of the well-defined form of theend stop and the well-defined contact pressure of the screw plug, anequally defined signal-to-noise ratio may be attainable.

[0013] In an example embodiment, the screw plug is may be contact with asealing surface of the housing, the sealing surface having a surfacequality such that an impervious connection may be able to be producedbetween the screw plug and the housing with the aid of the sealing ring.The screw plug may perform the sound-conducting function and the sealingfunction simultaneously. Thus, no further structural elements or aseparate assembly such as a tapped hole in the housing and a separatescrew plug may be necessary.

[0014] In an example embodiment, the housing is the housing of a gearunit including a lubricant, e.g., oil. This may provide that gear noisesare able to be monitored. Thus, e.g., tooth breakage, pitting and/oroverload impacts may be determined.

[0015] In an example embodiment, the housing of the gear unit may have atapped hole straight through for removing and/or pouring in lubricant.This may provide that the screw plug is usable as a sealing, releasablyconnectable oil drain plug, and at the same time is usable as aconductor for sound. It may even make two propagation paths availablefor the sound, e.g., via the screw thread on one hand, and via the endstop on the other hand.

[0016] In an example embodiment, the screw plug may have a cylindricalexternal thread for screwing into the tapped hole. This may provide thatan oblique position of the screw plug may be avoidable, and therefore awell-defined contact pressure, an equally defined sound transmission andan impervious seal at the entire periphery of the sealing surfaces maybe able to be produced.

[0017] In an example embodiment, mutually contacting surfaces, thetightening torque of the sensor against the screw plug and thetightening torque of the screw plug against the housing may be such thatacoustical vibrations are transmittable both by the first and secondtapped hole and via the end stop with a sufficiently goodsignal-to-noise ratio for the detection by sensor. In this context, itmay be provided that the sensor indeed has more than one connection—thusthe connection of its external thread and its cone to the second tappedhole with sinking—toward the housing, e.g., the end stop and theexternal thread of the screw plug, but nevertheless, very good soundtransmission, thus low damping, may be achievable.

[0018] In an example embodiment, the screw plug and the housing may bemade of a metallic material. This may make it possible to provide a muchhigher tightening torque than for a plastic implementation, a seal of ahigh protection class, and at the same time, good sound transmission.Implementation in plastic, on the other hand, may lead to a much poorersignal-to-noise ratio.

[0019] Aspects with respect to the screw plug are thus, e.g., that theseal may only be able to be compressed to a specified degree, since thescrew plug may only be able to be screwed in up to the end stop.Therefore, a well-defined sealing function of the same kind may alwaysbe able to be ensured, and the seal may be protected from destruction.In addition, a sealing surface, thus a machined surface, which thereforemay ensure the predetermined sealing function, may be provided on thehousing. Due to the cylindrical design of the screw thread of the screwplug, the axial guidance may be sufficient, that the screw plug is notaskew in the housing. In addition, with the aid of the end stop, adefined surface may be able to be provided, resulting in a definedpressure, because the screw plug may only be able to be screwed in up tothe end stop. Therefore, a well-defined signal-to-noise ratio may alsobe attainable.

[0020] Moreover, the screw plug may be able to be released and screwedin again without substantial loosening, etc. occurring. In addition,when screwing in, no shavings may be formed which may lead tocontamination or destruction.

[0021] After the screw-in operation, the end stop may also form aprotection for the sealing ring against the surroundings.

[0022] In an example embodiment, sealing ring 4 may be provided in sucha manner that it is able to be increasingly compressed during thescrew-in operation up to a maximum value determined by the end stop.Sealing ring 4 may be able to be positioned between two sealing surfaces(3, 7) whose direction of surface normal is parallel with respect to theaxial direction of the screw plug thread, and during the screw-inoperation, the distance between these sealing surfaces (3, 7) is able tobe reduced up to a value determined by end stop 5. The sealing ring maybe loaded as little as possible. During the screw-in operation, it maybe increasingly compressed only between the sealing surfaces, and maynot be pulled along and/or squeezed against the inner wall of the firsttapped hole.

[0023] Aspects with respect to the production series of devices are thatthe production series includes at least two sizes which includedifferent screw plugs, and the same sensor may be connectable to thesedifferent screw plugs for the at least two sizes. This may provide thatthe production series may feature a wide variety for satisfying customerwishes, and may be extremely inexpensive, compact and able to bemanufactured quickly and easily.

[0024] In an example embodiment, the sensor may be releasablyconnectable with its external thread to the tapped hole of the screwplug. All screw plugs for different sizes may be able to be equippedwith the same tapped hole, and therefore the sensor may be usable forall these sizes.

[0025] In an example embodiment, in the case of the screw plug, for atleast two sizes, the tapped hole for the connection to the sensor andthe external form, e.g., the external hexagon, may be implementeduniformly, and for these sizes, the external thread, the end stop and/orthe sealing ring may be implemented differently. For different sizes,the same tool may be used for tightening or loosening the screw plug,the same tool may be used for tightening or loosening the sensor, andnevertheless, different sizes of the devices, e.g., different wallthicknesses of the housing of the gear unit or of the geared motor, maybe usable for the same sensor.

[0026] Further features and aspects are set forth below.

[0027] Reference Numeral List

[0028]1 screw plug

[0029]2 second tapped hole with sinking

[0030]3 first sealing surface

[0031]4 sealing ring

[0032]5 end stop

[0033]6 external thread

[0034]7 second sealing surface

[0035]8 first tapped hole with internal thread, straight through

[0036]9 housing

[0037]31 external thread

[0038]32 cone

[0039]33 external hexagon

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 is a cross-sectional view an example embodiment of a deviceaccording to the present invention in an uninstalled state.

[0041]FIG. 2 is a cross-sectional view of the device illustrated in FIG.1 in an installed state.

[0042]FIG. 3 is a side view of an example embodiment of a deviceaccording to the present invention.

[0043]FIG. 4 illustrates an example embodiment of a production series ofthe present invention.

DETAILED DESCRIPTION

[0044] In FIG. 1, a second tapped hole 2 is introduced with sinking intoscrew plug 1 for the connection to sensor (31, 32, 33). Screw plug 1 isscrewed with its external thread 6 into a first tapped hole 8, whichpasses through the housing and has an internal thread, until end stop 5abuts. After applying a suitable tightening torque, the sound istransmitted very well via end stop 5 and second sealing surface 7. Atthe same time, the machining—actually provided because of the sealtightness—of the sealing surfaces, e.g., second sealing surface 7 andthe corresponding opposite surface of end stop 5, also has a positiveeffect on the transmission of structure-borne noise, because thecoupling is improved from the standpoint of acoustical engineering.Sound is additionally transmitted via first tapped hole 8. In addition,the sealing ring is compressed when applying the tightening torque.Therefore, screw plug 1 is joined to housing 9 via first sealing surface3 and second sealing surface 7 in a manner forming a seal, e.g., againstthe escape of lubricant.

[0045] Thus two paths are available for the propagation of sound fromthe gear unit toward the sensor, namely, via the screw thread on onehand, and via the end stop on the other hand. The sound transmission maytherefore be improved, as well as the signal-to-noise ratio.

[0046] Thus, only second sealing surface 7 may need to be machined withsufficiently high surface quality on housing 9.

[0047]FIG. 3 shows the sensor schematically. The sensor has an externalthread 31 for screwing into second tapped hole 2 with sinking, cone 32or the cone section being formed to correspond with the sinking in thecase of second tapped hole 2. In addition, the sensor has an externalhexagon 33 for the form-locking, releasable connection with a tool forthe tightening, such as, for example, a hexagon.

[0048]FIG. 2 shows the screw plug in the installed state. Sealing ring 4is squashed, and end stop 5 is arranged directly, under sufficientlygreat action of force, on second sealing surface 7, which may contributeconsiderably to the sound transmission.

[0049] The production series of gear units may feature several sizes.Since the wall thicknesses of the associated housing are different, thescrew plugs are also dimensioned accordingly. FIG. 4 shows three screwplugs matched to three sizes of the production series. On the housingside, they are designed differently with, e.g., different diameters c1,c2 and c3. On the sensor side, however, they have the same design with,e.g., the same overall size a and the same diameter b of the tappedhole. In the first place, the external form is implemented as anidentical external hexagon, and secondly, the second tapped hole withsinking is in each case also identical. Therefore, the same sensor mayalways be able to be connected. Thus, the production series may havegreat variance or variety, may satisfy customer wishes for gear units ofdifferent sizes with or without sensor, and may even require only onesensor for different sizes. The screw plug is, as it were, an adapterwhich permits the use of one sensor for several sizes. In addition, thescrew plug without sensor is usable as a sealing element. Moreover, itis possible to replace the screw plug by a different screw plug whichhas no partial areas projecting from the housing and, for example, hasan internal hexagon for the application of a tool.

[0050] An aspect of an example embodiment of screw plug 1 illustrated inFIG. 1 is also that end stop 5, because of its function of conductingsound, may be usable as a device for monitoring the connection of thescrew plug to the housing. The sound conductivity increases rapidlywhile screwing the screw plug into the housing after the end stop hasmade contact with the sealing surfaces. Therefore, the sound detectionof the sensor is able to detect whether the screw plug has been screwedin incorrectly, e.g., has not been screwed in completely.

1 to
 22. (Canceled).
 23. A device, comprising: at least one screw plugconfigured to be screwed into a first tapped hole of a housing, the atleast one screw plug including a seal arrangement configured to seal aconnection to the housing to form a seal, the at least one screw plugincluding a second tapped hole configured to releaseably connected to asensor, the at least one screw plug including an end stop configured toconduct acoustical waves and arranged as a mechanical limit for screw-inof the screw plug.
 24. The device according to claim 23, wherein theseal arrangement includes a seal ring.
 25. The device according to claim23, wherein the seal arrangement is configured to seal the connection tothe housing against escape of oil.
 26. The device according to claim 23,wherein the second tapped hole is configured to releaseably connect tothe sensor by a screw connection.
 27. The device according to claim 23,wherein the seal arrangement is configured to be increasingly compressedduring screw-in to a maximum value in accordance with the end stop. 28.The device according to claim 23, wherein the seal arrangement ispositionable between two sealing surfaces, the sealing surfaces eachhaving a direction of surface normal parallel to an axial direction ofthreads of the screw plug, a distance between the sealing surfacesreduceable by screw-in of the screw plug up to a value in accordancewith the end stop.
 29. The device according to claim 23, wherein thefirst tapped hole is arranged as a straight through tapped hole.
 30. Thedevice according to claim 29, wherein the screw plug arranged as an oildrain plug.
 31. The device according to claim 23, wherein the end stopis arranged on a larger diameter than the seal arrangement, the end stoparranged as a housing-part-forming protection for the seal arrangementin a screwed-in position of the screw plug.
 32. The device according toclaim 23, wherein the screw plug is arranged to project from the housingin a screwed-in state with an external form protrusion, the screw plugreleaseable and reconnectable with a tool releaseably connectable withthe external form protrusion with form locking.
 33. The device accordingto claim 23, wherein the device is arranged as at least one of a gearunit and a geared motor.
 34. The device according to claim 32, whereinthe external form protrusion includes an external hexagon.
 35. Thedevice according to claim 23, wherein the second tapped hole includes acountersink, the second tapped hole configured to releaseably connect toa sensor including an external thread corresponding to the second tappedhole and a cone section corresponding to the countersink.
 36. The deviceaccording to claim 23, wherein the sensor is configured as at least oneof a vibration sensor and a sensor arranged to detect acousticvibrations at least in a subrange of a range between 0 Hz and 10 MHz.37. The device according to claim 23, wherein the seal arrangement isconfigured for impervious connection to the housing.
 38. The deviceaccording to claim 23, wherein the screw plug is configured to contact asealing surface of the housing, the sealing surface including a surfacequality configured to produce an impervious connection between the screwplug and the housing by the seal arrangement.
 39. The device accordingto claim 23, wherein the housing is arranged as a housing of a gear unitincluding a lubricant.
 40. The device according to claim 39, wherein thelubricant includes oil.
 41. The device according to claim 23, whereinthe housing is arranged as a housing of a gear unit, the first tappedhole arranged straight through the housing and arranged to at least oneof remove and pour out of lubricant.
 42. The device according to claim23, wherein the screw plug includes an external thread configured toscrew into the first tapped hole.
 43. The device according to claim 23,wherein the screw plug is arranged to seal a straight-through housingopening of a housing fillable with oil.
 44. The device according toclaim 23, wherein acoustical vibrations are transmittable via the firsttapped hole, the second tapped hole and the end stop and in accordancewith mutually contacting surfaces, a tightening torque of the sensoragainst the screw plug and a tightening torque of the screw plug againstthe housing with a sufficient signal-to-noise ratio for detection by thesensor.
 45. The device according to claim 23, wherein the screw plug andthe housing are formed of a metallic material.
 46. A production series,comprising: a plurality of devices, each device including at least onescrew plug configured to be screwed into a first tapped hole of ahousing, the at least one screw plug including a seal arrangementconfigured to seal a connection to the housing to form a seal, the atleast one screw plug including a second tapped hole configured toreleaseably connected to a sensor, the at least one screw plug includingan end stop configured to conduct acoustical waves and arranged as amechanical limit for screw-in of the screw plug, the production seriesincluding at least two sizes, each size including a different screwplug, the different screw plugs for the at least two sizes configured toconnect to a same sensor.
 47. The production series according to claim46, wherein the sensor is releaseably connectable by an external threadto the second tapped hole.
 48. The production series according to claim46, wherein the second tapped hole and an external form of the screwplug are uniformly configured for the at least two sizes, at least oneof an external thread, the end stop and the seal arrangement configureddifferently for the at least two sizes.
 49. The production seriesaccording to claim 48, wherein the external form includes an externalhexagon.
 50. A device, comprising: at least one screw plug for screwinginto a first tapped hole of a housing, the at least one screw plugincluding means for sealing a connection to the housing to form a seal,the at least one screw plug including a second tapped hole forreleaseably connecting to a sensor, the at least one screw plugincluding an end stop for conducting acoustical waves and arranged as amechanical limit for screw-in of the screw plug.